Functional Failure
A functional failure occurs when an asset or system can no longer perform a required function to the specified performance standard.
What this term means in maintenance
A functional failure occurs when an asset or system can no longer perform a required function to the specified performance standard.
What functional failure means
A functional failure is defined against what the asset is required to do.
Examples include:
- Pump cannot deliver required flow
- Generator cannot start on demand
- Temperature sensor cannot measure within tolerance
- Conveyor cannot operate at required speed
- Safety valve cannot open at the specified pressure
Complete and partial failure
A failure may be complete, where the function is lost entirely, or partial, where performance falls below the required standard.
Practical example
A pump is still running but can deliver only 60% of the required flow. It has not stopped, but it has functionally failed because it no longer meets the process requirement.
Why the performance standard matters
“Pump operates” is too vague. A useful function includes capacity, accuracy, speed, quality, safety, or other measurable requirements.
Common mistake
Defining failure only as total equipment stoppage ignores degraded conditions that already affect production, quality, energy, or safety.
Related concepts
Related maintenance terms
Keep exploring connected CMMS, reliability, and maintenance planning terms.
Potential Failure
A potential failure is an identifiable condition showing that an asset is beginning to deteriorate and may progress toward functional failure.
Failure Mode
A failure mode describes the specific way an asset, component, or function fails to meet its required performance.
Reliability-Centered Maintenance
Reliability-Centered Maintenance, or RCM, is a structured method for selecting maintenance and risk-control tasks based on asset functions, failure modes, consequences, and technically effective actions.
Glossary FAQs
- What is a functional failure?
It occurs when an asset can no longer meet a required function or performance standard.
- Can equipment functionally fail while still running?
Yes. Reduced capacity, accuracy, speed, or quality can be a functional failure.
- Why define performance standards?
They make it clear when equipment no longer meets the business or process requirement.